🌐 IP Subnet Calculator (Flask)

A world-class, modular, and secure open-source web application for IP and subnet calculations. Built for production use, recruiter evaluation, and security auditor review.

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🚀 Problem Statement

Modern networks require accurate, secure, and user-friendly tools for subnet calculation and IP analysis. This project delivers a scalable, extensible, and production-ready solution for both IPv4 and IPv6, with a strong emphasis on:

• Code quality
• Security best practices
• Maintainability
• Professional documentation

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🏗️ Architecture & Tech Stack

• Python 3.8+
• Flask (Web Framework)

Project Organization

.
├── src/            # Core application logic (SOLID, DRY)
├── config/         # Environment & configuration
├── tests/          # Unit & integration tests (pytest)
├── docs/           # Architecture, changelog, security, contributing
├── scripts/        # Automation & developer utilities
├── .github/        # CI/CD workflows (GitHub Actions)

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✨ Features

• ✅ IPv4 and IPv6 subnet calculations
• ✅ Subnet mask, CIDR, wildcard, and host range computation
• ✅ Download calculation results as CSV
• ✅ Secure-by-default configuration
• ✅ Modular, testable, and extensible architecture
• ✅ Production-ready documentation and ownership model

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⚡ Quick Start

1️⃣ Clone the repository

git clone https://github.com/JosephJonathanFernandes/ip-subnet-calculator-python
cd ip-subnet-calculator

2️⃣ Install dependencies

pip install -r requirements.txt

3️⃣ Set environment variables

cp config/.env.example config/.env

Set a secure secret key inside config/.env:

FLASK_SECRET_KEY=your-secure-secret-key

4️⃣ Run the application

flask run

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🧪 Testing

All core logic is fully tested using pytest.

pytest --cov=src

• 🎯 Coverage Goal: 90%+ for core logic

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🧹 Linting & Formatting

• Linting

flake8 src/ tests/

• Formatting

black src/ tests/

• Pre-commit Hooks See .pre-commit-config.yaml

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🔄 CI/CD

Automated using GitHub Actions (.github/workflows/ci.yml):

• Runs lint checks
• Executes unit & integration tests
• Measures test coverage
• Triggered on every push and pull request

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🔒 Security

• 🔐 No hardcoded secrets (.env.example provided)
• 🛡️ All user input validated and sanitized
• 🌐 Secure HTTP headers enabled by default
• 📄 See SECURITY.md for full security policy

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Contribution

• Contributing: See CONTRIBUTING.md

Contributions are welcome and encouraged!

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💡 Project Value

• ⭐ Recruiter- and reviewer-friendly
• 🧩 Clean, maintainable, and extensible codebase
• 🔐 Secure by default
• 🚀 Ready for production and open-source adoption

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📝 Documentation

• ARCHITECTURE.md – High-level system design
• CHANGELOG.md – Release history
• CONTRIBUTING.md – Contribution guidelines
• SECURITY.md – Security policy

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🛠️ Developer Experience

• Recommended: pre-commit hooks
• Enforced linting & formatting
• Automated CI/CD ensures code quality on every PR

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📄 License

This project is licensed under the MIT License.